Nicotinamide adenine dinucleotide (NAD) plays a fundamental role in both cellular energy metabolism and cellular signaling. NAD plays an important role in energy metabolism, as the pyridine ring in the NAD molecule readily accepts and donates electrons in hydride transfer reactions catalyzed by numerous dehydrogenases. The enzyme nicotinamide phosphoribosyltransferase (NAMPT, NMPRT, NMPRTase, or NAmPRTase, International nomenclature: E.C. 2.4.2.12), promotes the condensation of nicotinamide with 5-phosphoribosyl-1-pyrophosphate to generate nicotinamide mononucleotide, which is a precursor in the biosynthesis of NAD.
NAMPT is implicated in a variety of functions, including the promotion of vascular smooth muscle cell maturation, inhibition of neutrophil apoptosis, activation of insulin receptors, development of T and B lymphocytes, and reduction of blood glucose. Thus, small molecule NAMPT inhibitors have potential uses as therapies in a variety of diseases or conditions, including cancers involving solid and liquid tumors, non-small cell lung cancer, leukemia, lymphoma, ovarian cancer, glioma, breast cancer, uterine cancer, colon cancer, cervical cancer, lung cancer, prostate cancer, skin cancer, rhino-gastric tumors, colorectal cancer, central nervous system (CNS) cancer, bladder cancer, pancreatic cancer and Hodgkin's disease. NAMPT inhibitors also have potential uses as therapies for diseases or conditions such as cancer, rheumatoid arthritis, diabetes, atherosclerosis, sepsis, or aging.
Rongvaux et al. have demonstrated that NAMPT is implicated in the regulation of cell viability during genotoxic or oxidative stress, and NAMPT inhibitors may therefore be useful as treatments for inflammation. Rongvaux, A., et al. J. Immunol. 2008, 181, 4685-4695. NAMPT may also have effects on the reaction of endothelial cells to high glucose levels, oxidative stress, and aging. Thus, NAMPT inbhitors may enable proliferating endothelial cells to resist the oxidative stress of aging and of high glucose, and to productively use excess glucose to support replicative longevity and angiogenic activity.
In particular, NAMPT inhibitors have been shown to interfere with NAD biosynthesis and to induce apoptotic cell death without any DNA damaging effects or primary effects on cellular energy metabolism, and thus have important anti-tumor effects. For example, the NAMPT inhibitor FK866 has these biochemical effects, and has also been shown to reduce NAD levels, induce a delay in tumor growth and enhance tumor radiosensitivity in a mouse mammary carcinoma model. See, e.g., Hasmann M. and I. Schemainda, “FK866, a Highly Specific Noncompetitive Inhibitor of Nicotinamide Phosphoribosyltransferase, Represents a Novel Mechanism for Induction of Tumor Cell Apoptosis,” Cancer Res. 2003, 63, 7436-7442: Drevs, J. et al., “Antiangiogenic potency of FK866/K22.175, a new inhibitor of intracellular NAD biosynthesis, in murine renal cell carcinoma,” Anticancer Res. 2003, 23, 4853-4858.
More recently, another NAMPT inhibitor, CHS-828, has been shown to potently inhibit cell growth in a broad range of tumor cell lines. See Olesen, U. H. et al., “Anticancer agent CHS-828 inhibits cellular synthesis of NAD,” Biochem. Biophys. Res. Commun. 2008, 367, 799-804; Ravaud, A. et al, “Phase I study and guanidine kinetics of CHS-828, a guanidine-containing compound, administered orally as a single dose every 3 weeks in solid tumors: an ECSG/EORTC study,” Eur. J. Cancer 2005, 41, 702-707. Both FK866 and CHS-828 are currently in clinical trials as cancer treatments.
There remains a need for potent NAMPT inhibitors with desirable pharmaceutical properties. Certain pyridinyl and pyrimidinyl sulfoxide and sulfone derivatives have been found in the context of this invention to have NAMPT-modulating activity.